Shorting plunger



1954 w. F. WILLIAMS ET AL 2,666,136

SHORTING PLUNGER Filed March 27, 1951 INVENTORS N Wms'ronE 'Wuums BY [0 WM M P401408 A TTORNE Y Patented Jan. 12,1954

SHORTIN G PLUNGER Winston F. Williams and Edwin N. Phillips, Cedar Rapids, Iowa, assignors to Collins Radio Company, Cedar Rapids, Iowa, a corporation of Iowa Application March 27, 1951, Serial N0. 217,787

2 Claims.

This invention relates in general to means for shorting energy travelling in'a wave guide and in particular to a shorting plunger. It is oftentimes desirable to vary the length of a wave guide as, for example, with a shorting plunger'and in order to short out the voltage vectors within the guide it is necessary to have a conducting member which forms a' low resistance path between the top and the bottom of the wave guide. It is imperative that the plunger make good contact with the wave guide at either side so its resistance will be maintained low. Prior to this invention fingers under spring tension have been used as shorting plungers but have the disadvantage that the fingers scratch and soar the inner surface of the wave guide, or alternately become deflected so as not to engage opposite sides of the Wave guide.

It is an object of this invention, therefore, to provide a shorting plunger which may be easily moved longitudinally of the wave guide while maintaining good contact with the upper and lower surfaces of the guide and which does not mar or scratch the surfaces.

Another object of this invention is to provide a shorting plunger for a wave guide which does not depend upon spring-loaded fingers to make contact with the side walls of the wave guide.

Still another object of this invention is to pro vide an improved and easily manufactured shorting plunger for a wave guide.

A feature of this invention is found in the provision for a pair of endless belts mounted on rollers adjacent each other so that they have a common side in contact and the opposite sides in contact with opposite sides of a wave guide.

Further objects, features, and advantages of this invention will become apparent from the following description and claims when read in view of the drawings, in which:

Figure 1 illustrates a shorting plunger of this invention;

Figure 2 is a sectional view taken on line 2-2 illustrating the shorting plunger in its operating position in a wave guide section; and

Figure 3 is an end view illustrating the shorting plunger of this invention in the wave guide.

Figure 1 illustrates the shorting plunger of this invention which comprises a pair of end plates I0 which have rotatably supported therebetween a plurality of rollers for carrying a pair of endless belt [9 mounted therein with rollers l4 and I6 rotatable'supported at the upper corners of the plates l0, and rollers l1 and I8 rotatably mounted at opposite edges of the plates I9 justabove their centers.

The endless belt I9 which might be made of copper foil or of some metal of high conductivity is mounted on the rollers l4, l6, I1 and I8 between the end plates ID. The belt I9 may also be made of webbing from conducting-material. The belt I9 is narrower than the distance between the plates [0. Between rollers l4 and I8 in plates ID are mounted a pair of supporting rollers 2| and 22 which engage the center portion of the belt [9 to maintain it in contact with the upper surface of the wave guide.

A pair of rollers 23 and 24 are rotatably supported in the end plates ID at the lower corners thereof and rollers 26 and 21 are rotatably supported at the opposite edges of the plates l9 slightly below the center of plate [0. A second flexible belt 28 of conducting material is mounted on rollers 23, 24, 26 and 21. A pair of supporting rollers 29 and 3| are rotatably supported along the bottom edges of the plates In between rollers 23 and 24. The rollers mounted in the end plates [0 are formed with small projections 32 at either end thereof and these projections are received within bearings 34 mounted in the end plates so that the rollers may rotate freely relative to the plates.

A slot 36 is formed in the center of either end plate It and a block 3'! is slidably received therein. A spring 38 is mounted between the lower end of the slot 36 and the lower edge of the block 3! to normally urge the block upwardly. A roller 39, best shown in Figure 2, is formed with projections 4| at either end thereof which are received in bearings 42 in the blocks 31. As shown in Figure 2, the roller 39 is mounted below the belts I9 and 28 and serves as an idler roller to maintain the belts taut and in electrical contact. Since the block 31 is free to move up and down in the slot 38, the tension will be maintained at all times.

With reference to Figure 3, the shorting plunger of this invention is shown within a rectangular wave guide having an upper wall 43, a lower wall 44, and end walls 46 and 41, respectively. It is to be noted that the distance between plates I0 is less than the distance between end walls 46 and 41 so that the plunger may be received therein. The belts I9 and 28 maintain electrical contact with the upper wall 43 and the lower wall 44 of the wave guide and thus short-out the energy 3 travelling down the wave guide. The side view of Figure 2 illustrates how the belts l9 and 28 contact the upper and lower walls 43 and 44.

In operation, the edge of the plunger farthest from the handle I3 is inserted into the wave guide and the handle pushed to move the plunger within the wave guide. The rollers I4, I 6, l'l l8, 2!, and 22 rotate counterclockwise and rollers 23, 24, 26, 21, 29, 3| and 39 rotate clockwise. The portions of the belts in contact passing over the roller 39 between rollers l8 and 1 move with the same speed and in the same direction. The rollers minimize friction and; the plunger may be easily moved in and out of the wave guide.

When the plunger is pulled out of the wave guide, the direction of rotation of the rollers will reverse.

It is seen that this invention provides an improved shorting plunger which always maintains good contact with the upper and lower walls of a wave 'gfii'de withcut' scarring them. Friction is also minimized sothat the plunger freeiy meted in and cat or the waveguide.

Al'though the invention has-been described with respect to a preferred embodiment thereof it is not to be so limited as changes and modifications may be madetherein which are within the full intended scope of the ini' ention as defined by the appended claims. 7

We claim: I

'1. A shorting plunger for a rectangular wave guide comprising, a pair of generally rectangular end plates received within said wave guide with the plane of said end plates being normal to the long sectional axis of said wave guide, a first roller rotatably" supported between said end plates adjacent their upper edges so that a portion of the rollers periphery extends above the end plates, a second roller rotatably supported between the' end plates longitudinally displaced from the first roller and a portion of the second roller extending above the edge of the end plates, third and fourth rollers rotatably supported between the end plates adjacent the longitudinal center line of the end plates, fifth and sixth rollers supported between the end plates below the third and fourth rollers, seventh and eighth rollers rotatably supported between the end plates near the lower corners thereof with a portion of their peripheries extending down below the end plates, said third and fifth rollers mounted directly below the first roller on a line transverse to the axis of the wave-guide,.' a. first flexible conducting belt rotatabl'y supported by said first, second, third and fourth rollers, a second flexible conducting belt rotatably supported by the fifth, sixth, seventh and eighth rollers, said first and second belts in contact between the third and fifth and fourth and sixth rollers, and means for moving said plunger connected to said end plates and extendin'g longitudinally of the were guide.

2-. An apparatus according tc claim 1 wherein an idler roller is mounted in said end plates by means including, a flexible block received in a transverse slot formed in each or said end plates, an idler roller rotatably supported between said block's, tensioning means urging said blocks toward one end of said slot and said first and second belts passing over said idler roller on the side toward whichsaid flexible means biases the roller.

WINSTON F. WILLIAMS. EDWIN N. PHILLIPS.

References Cited in the" file Of this patent UNITED STATES PATENTS Number Name Date 520,106 Cox May 22, 1894 2,467,758 Lindenblad Apr. '19, 1949 2,535,480 Begun -l Dec. 26, 1950 

